From the specs they look pretty good, if your pre/amp were in use while on the space shuttle during takeoff. Outside of that, how do they look? I have a bid in for one lot just to play with 'em, I'm diggin' the metal casing.

I built a stepped attenuator from Russian RES-47 relays some time ago. The issue is you don't know the contact resistance and capacitance, and it was a bit noisy in action for me. Also one failed after some time. Now I'd use mercury-wetted reed relays. Better you open one and see what is inside.